The present invention relates to the installation of an optical component in an optical device, and more particularly to a structure for installing an optical component which should be installed inside a housing of an optical device, but should be connected to an external part arranged outside the housing.
In the prior art, a known optical component of this type is a collimator unit mounted in a light scanning device to be employed in, for instance, a laser beam printer.
Usually, the collimator unit comprises a light emitting source such as a semi-conductor laser, a collimator lens for converting the light emitted from the light emitting source to a parallel flux, a casing for accommodating the light emitting source and the collimator lens, and a circuit board for controlling the light emitting source. A connector is to be provided to the circuit board for receiving control external signals.
One example of a conventional installation structure for a collimator unit is as illustrated in FIG. 1. In FIG. 1, a small-diametered front portion 107A of a casing 107 of a collimator unit 101 is inserted into a housing 113 through a through-hole 113A formed thereon, and is fixed thereto by a pair of screws 117, 117 which are inserted into the screw holes 113B, 113B formed on the housing 113 through the rear flange portion 107B of the casing 107. A connector 111 is mounted on a circuit board 109 secured to the back surface of the casing 107 formed with a pair of holes 109A, 109A for passing the screws 117, 117 therethrough, respectively.
With this prior installation structure, however, the collimator unit 101 must first be abutted to the housing 113 from external side and then fixed thereto by threading the screws 117, 117 while maintaining the optical axis of the collimator unit 101 coincident with those of other optical components to also be arranged inside the housing 113. Accordingly, it is not easy to leave the fitting thereof to an automatic assembling system with assuring to seat the collimator unit 101 with high positional accuracy.
Another example of the conventional installation structure is as illustrated in FIG. 2. In FIG. 2, a casing 207 as well as the control circuit board 209 are installed inside the housing 213. More particularly, the collimator unit 201 is provided with the bottom plate portion 201A extended along the optical axis of the collimator unit 201, while a receiving recess 213b is formed on the bottom portion of the housing 213 for receiving the bottom plate portion 201A thereinto and to be fixed thereto by the pair of screws 217, 217.
With this prior art installation structure, however, a harness 219 of a connector 211 or the like must be passed through the bottom portion of the housing 213 to be connected to an external part, where a sealing material 220 or the like should be applied, which is troublesome and makes it difficult to have installation of the collimator unit 201 performed by automatic assembling system.